Aqueous wood finishing composition of urea-formaldehyde condensate, sugar and solvent



Feb. 20, 1962 J M BERRY AQUEOUS WOOD FINISHING oMosITIoN OF UREA-FORMALDEHYDE CONDENSATE, SUGAR AND SOLVENT Filed May 14, 1958 WATER DISPERSE RE SIN IN WATER ADD CARBOHYDRATE ADD SPREADING AGENT DILUTE DISPERSION WITH ADDITIONAL WATER INVENTOR. JOHN M. BERRY ATTORNEYS 3,5322258 Patented Feb. 20, 1962 {ice 3,022,258 AQUEUUS WQOD FINiSi-IING CUMPOSKTEGN F UREA-FORMALDEHYDE CONDENSATE, SUGAR AND SGLVENT John M. Berry, Martinsville, 7a., assignor to Midland Chemical Corporation, Dayton, Ohio, a corporation of Delaware Filed May 14, @523, Ser. No. 735,233 2 Claims. (61. zen-17.3)

This invention relates to wood finishing and particularly to filler-sealer compositions and to methods of applying the filler-sealer compositions.

In the finishing of wood it is customary to apply to the smooth, sanded wood which is to be finished first a stain, then a filler followed by a sealer, and finally a finish coat. The stain is utilized to give color to the wood and to enhance the appearance of the grain; the filter serves to close the pores and tiny crevices of opengrained wood and in the case of some close-grained Woods may be eliminated; the sealer is applied to close, and as its name implies, seal the wood pores; the finish coat is a protective coating. I

This invention contemplates the provision of a fillersealer composition wherein the filling and sealing components are dispersed in an aqueous system. Such com positions have particular utility when employed on wood surfaces treated with the fixing agent of my co-pending application, Serial No. 735,237, filed May 14, 1958, and

entitled: Aqueous Wood Fixing Composition and Process of Fixing a Wood Surface, and are receptive to the usual finish coats such as lacquers, varnishes and the like.

T he invention particularly contemplates the provision of novel wood filler-sealer compositions wherein the grain of the wood is not substantially raised, a factor which has heretofore limited the utility of Water as a major solvent in wood finishing applications.

The filler-sealer compositions of this invention are preferably applied by spray methods and all hand fiiler wiping methods generally practiced in conjunction with conventional filling operations are then eliminated.

The compositions of invention include as prime components: (a) a water dispersible carbohydrate which'does not furnish aldehyde or ketonic groupings in any sub-' stantial quantityparticularly sucrose; (11) 'an aminoplast-aldehyde resin which is subject to being cured and which is preferably in a B stage in the form of a finely divided powder; and (0) water to effect a dispersion of the carbohydrate and aminoplast-aldehyde resin.

To aid even flow of the aqueous dispersion on the woodparticularly the close-grained woodsthere is suitably added a spreading agent. Such is not an absolute necessity with open grain woods. Useful spreading agents include the allcyl ethers of the ethylene glycolsfor example the mono-butyl ether of diethylene glycol (Butyl Carbitol); also useful in combination with the said mono-butyl ether of diethylene glycol is the mono-butyl ether of ethylene glycol (Butyl Celiosolve) which in mixture is suitably present to the extent of about /3 of the diethylene glycol.

In addition the Butyl Carbitol serves as a timer for controlling evaporation of the Water from the applied film, so that time may be had for the desired filling and sealing. The Butyl Cellosolve functions also to improve adhesion to succeeding top coats. The Butyl Cellosolve is itself somewhat limitedly Water miscible, but is sufficiently so to aid the Butyl Carbitol in attaining spreadability. I

The aqueous system on drying and hardening forms a homogeneous, transparent, insoluble product in the form of a film. This film is hard and readily sanded before application of the finish coat or coats.

The aminoplast-aldehyde resins include those synthetics derived from the amino, imino and amido or imido compounds, one example being urea formaldehyde and another melamine formaldehyde.

Urea formaldehyde, as a dry partially polymerized powder having a particle size of about 30.n1esh, has been found most suitable; other characteristics of one such suitable resin include a Stormerv viscosity of 2040 rpm. at 21 C. (50 grams of water plus 100- grams of the resin); a gel time at 70 F. of 99-140 minutes (100 grams of the resin and 50 grams 4% ammonium chloride solution).

The carbohydrate most useful, due primarily to economic reasons, is sucrose; the sucrose (cane or beet sugar) dissolves readily in the water of the composition and appears to aid dispersion of the resin.

The sugar serves not only as a filler but also aids the sanding of the hardened film; this is probably due to the formation of a complex between the sucrose and resin which limits crystallinity in the film. This also contributes to the film integrity and film clarity. However, the film as a whole is amorphous and the sugar relative to the resin should be so limited in amount as to inhibit crystalline formationto the extent that water solubility results. In general, the sugar-resin ratio by weight may be from 1:1 to 1:3 without encountering difficulty from crystallinity or water solubility of the product film. Such ratio may, however, vary somewhat with the specific resin employed.

The resin which must be a resin which disperses colloidally, when used to form a film without the carbohydrate, results in a cloudy, somewhat opaque film. Such is usually undesirable and the carbohydrate addition functions to overcome this by acting to clarify the film.

In practice the resin is first added to the water with simpie mixing equipment agitation; the dispersion is whitish, having somewhat the appearance of latex; the sucrose is then added while mixing and the sugar appears to assist the dispersibility of the resin- The resin is itself hydrated by contact with the water and the dis persion is in the form of a suspension. To the suspension the Butyl Carbitol and Butyl Cellosolve may be added while mixing. The Butyl Carbitol also appears to help the dispersion of the resin, and in the film it also serves as a timer to control evaporation so that desired filling and sealing is achieved.

When the aqueous filler-sealer described is applied to the hard fixing agent film formed as set out in my copending application referred to hereinbefore, the water of the filler-sealer composition tends to dissolve and react with the fixing agent or stain film and solids of the filler- .sealercompletes filling of the wood pores.

The filler-sealer after-application is permitted to air dry; air drying alone may be utilized, this requires normally 3-4 hours to attain a hardened film. However, a short period of air dry, about /1 hour, followed by oven drying for 13 hours at F. F. may also be employed.

When used in conjunction with the fixing agent-stain of my co-pending application, no additional ingredient is required for the hardening or cure of the resin. However, when the surface to which the filler-sealer is applied is not a source of acid or hydrogen ions upon wetting, then a catalyst must be added to the filler-sealer composition. This catalyst may be boric acid, ammonium chloride or other acidic forming substance.

. 3 The accompanying drawing illustrates the steps of the procedure in the formation of the filler-sealer.

Typical composition formulations are:

Example A Sugar pounds. Urea-formaldehyde (powdered stage-B resin) pounds. Mono-butyl ether of diethylene glycol (Butyl Carbitol) 4 pounds (about /2 gallon). Mono-butyl ether of ethylene glycol (Butyl Cel.losolve) liquid ounces (about 1.2 pounds). Water 2 /2 gallons.

Example B Sugar 10 pounds. Urea-formaldehyde (powdered stage-B resin) 15 pounds. Mono-butyl ether of diethylene glycol (Butyl Carbitol) 4 pounds. (about /2 gallon). Mono-butyl ether of ethylene glycol (Butyl Cellosolve) 2O liquid ounces (about 1.2 pounds). Water 19.8. pounds (2.3 gallons).

As in Example A, the urea-formaldehyde is first dispersed in the water and the sugar is then added, followed by the addition of the Butyl Carbitol and Butyl Cellosolve.

In each of the foregoing examples the filler-sealer composition is clear, that is, there is no pigment or dye added.

Example C A white pigmented fill-seal may be formed as follows:

Titanium dioxide; pounds 2 Clear fill-seal of Example A or B gallons 1 This composition is ground in a pebble mill or other suitable grinding equipment.

Example D A water type dye may be incorporated in:

Ounces Calcocid ScarletMoO cone 5 Yellow Powder #700 1 Bufialo Black nBR 126% /2 To the above add 1 gallon of the clear fill-sealer of Example A or B.

It is to be particularly noted that. no heating is required for the formation of the compositions and that only sim- 4 pie mixing equipment, such as stirrers, is necessary to effect the dispersion of the material.

The resin employed, Whether it be urea-formaldehyde or melamine formaldehyde ismost suitably in a B stage, in which it is Water dispersible, but hardenable upon contact with an acid catalyst to insoluble state.

Particularly it is to be noted that the resultant film is transparent. While such is not essential for wood finishing, it is desirable in order to clearly expose the grain of the wood.

The composition itself is on the neutral to alkaline side, having a pH'frorn about 7 to about 8.5.

To effect the cure of the filler-sealer composition, the composition may be acidified. However, the shelf life of the product will be materially shortened by the incorporation of acids or salts, as ammonium chloride.

Accordingly, for commercial purposes, it is preferable to supply the composition in the alkaline state, the necessary catalyst addition being made upon use, either by direct addition to the suspension or by contact of the suspension with a surface embodying the catalytic agent.

In general, the solids components should be at least about 40 percent by weight of the composition, and the sugar component preferably comprises about 25 percent of the solids.

The composition of invention as described has a long shelf life in the absence of an acid addition; such acid addition, if made, is made just prior to use.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What is claimed is: 1. An aqueous filler-sealer composition for filling an sealing wood surfaces which consists essentially of Sugar pounds.. 5 Urea-formaldehyde (powdered stage-B resin) d0 15 Monobutyl ether of diethylene glycol do 4 -Monobutyl ether of ethylene glycol liquid ounces 20 Water gallons 2 /2 2. An aqueous filler-sealer composition for filling and sealing wood surfaces which consists essentially of Sugar .pounds 10 Urea-formaldehyde (powdered stage-B resin) do 15 'Monobutyl ether of diethylene glycol do 4 Monobutyl ether of ethylene glycol liquid ounces 20 Water pounds 198 References Cited in the file of this patent UNITED STATES PATENTS mash. 

1. AN AQUEOUS FILLER-SEALER COMPOSITION FOR FILLING AND SEALING WOOD SURFACES WHICH CONSISTS ESSENTIALLY OF 